Is it possible to get a penetrating tone on a trombone. Like switch from smooth to penetrating like a trumpets. Without switching mouthpieces. I use a 6AL, 12C, 14D, 12E depending on what music is played.

Practice both types of tone. Take it into your warm-up/practice routine and try to get the sound YOU want. The important part is being able to hear that sound. if you dont know exactly what that sounds like your going to have problems.

You want to penetrate? you cant handle the penetration.

Look i have found that "penetration" is really a bad thing for trombone playeres. I adjudicate contests every now nad then and here is my bigest problem wiht highschool bands, and even some college bands. People dont know how to blend. In a symphony,in bands and even "big bands" you want to sound like there is only one person playing, individual players should never be heard (excepting solos.

good luck.

So what is the best way to play as loud as the trumpets. They have an easier time of it since they cut through easily. I often feel that my section is being drowned out by trumpet players.

You want to be heard. I see. Well to be heard "bells up" you have one of just a few instruments that has a bell facing forward. move your stand so that you have nothing obstructing your sound. Trumpets often stqand and there bells are over the top of the stand. You might want to think about where they are in relation to you. if your ina semi circle arangement(most bands are) and your on one side and there oposite of you they might be "we got to play louder than the trombones"
Lastly to play really loud practice 2 things 1 breath control and 2 play as softly as you can and still retain tone control. Both will make it easier to play loud with out playing splattisimo.